1. (Industrial useful field)
This invention relates to a three-element torque converter suitable mainly for a vehicle.
2. (Prior art)
In a conventional ordinary three-element single-stage two-phase torque converter, a torque ratio at time of low speed-ratio is increased by fixing a stator at time of low speed-ratio and by permitting it to rotate in a normal direction at time of high speed-ratio. However, the torque ratio is only about 3-3.5 in this case, which is not sufficient for ordinary application.
On the other hand, in a four-element two-stage torque converter, the stator is divided into two halves one half of which is rotated in a direction opposite to the other, and a reverse torque is combined with a turbine output to generate a high torque-ratio. In this case, however, its structure becomes complicated to cause a high cost to manufacture.
The inventor of the present invention has sought to provide a three-element torque converter which is able to increase a torque-ratio at time of low-speed range by the use of a planetary gear mechanism.
3. (Object of the invention)
An object of the invention is to provide a three-element multi-stage torque converter which is able to increase a torque-ratio at time of a low speed-ratio.